GEOMETRIC STRUCTURE AND VIBRATION FREQUENCIES OF RE2F8

A complex electron diffraction and mass spectrometric investigation of the saturated vapor of rhenium tetrafluoride has been carried out. Th e principal molecular form in the vapor phase at T = 471 K is the dime r Re2F8. The geometric structure of the Re2F8 molecule has the equilib rium eclipsed conformation of symmetry D-4h with a triple bond, Re=Re. The barrier to internal rotation of the ReF4 groups relative to one a nother is 2.8 +/- 2.8 kJ/mole. The vibration frequencies of the Re2F8 molecule have been estimated on the basis of the experimental amplitud es of vibration.